Steps to reproduce:
- Use ecommerce and the mollie payment
- Open two tabs, on one pay via mollie, on the other
while the mollie payment is in progress add or
remove items to the cart

Current behavior:
Once the payment is validated the customer is redirected to
a page that show a wrong value for the transaction, and there
is nothing about the amount mismatch

Expected behavior:
The transaction has the right value and the text in warning
explains the situation.

opw-2983494

closes odoo/odoo#101079

X-original-commit: 0c0dae30
Signed-off-by: William Braeckman (wbr) <wbr@odoo.com>
Signed-off-by: Fockedey Martin (mafo) <mafo@odoo.com>